Such mirrors are in common use, but sometimes suffer with the disability that the spring rate is such that the members disengage and require a re-engagement operation which is difficult to achieve. Under extreme impact conditions, it is possible for a spring (in a prior art mirror) to be stretched beyond its elastic limit and become useless.
The main object of this invention is to provide improvements wherein the difference in pressure applied by the spring during deflection will be less than the difference with a spring arrangement as presently used, that is, the spring rate will be improved in that it will be lower, and wherein the cost of manufacture can be reduced.